Invalid Materialized View

Hello,

I am working on upgrade Oracle and got one object invalid after running pre-upgrade tool:

.... USER CUSTOMER has 1 INVALID objects.

If I select using dba_objects I can see mentioned view:

SQL> select * from dba_objects where status='INVALID' and owner in ('CUSTOMER');

CUSTOMER                       MV_SUBJECTS

    292511                MATERIALIZED VIEW   08-APR-19 08-APR-19 2019-04-08:14:42:16 INVALID N N N

        19

However when I check dba_mviews it returns nothing:

SQL> select owner, MVIEW_NAME from dba_mviews where owner in ('CUSTOMER') and MVIEW_NAME='MV_SUBJECTS';

All others VALID MVs are visible in both. Any idea why this particular one is not in dba_mviews and more important how to fix this invalid status before upgrade ?